2 – Martin Mahogany Acoustic Bolt on Neck Up for auction is 2 NEW Martin Mahogany Acoustic Bolt on Neck. Each of these necks bolt on at the 14th fret. Each of these necks have a split on the head stock (Please See Pictures) but are in good overall condition. If you have any questions please feel free to contact me! Thanks for looking and I hope you are the lucky bidder! Thanks again!